This is a Mastery Bridge, known for its high precision. I bought it over 10 years ago, but during a live performance, one of the screws and springs that secure the saddles came loose and got lost, so I haven't used it and have kept it in storage. Therefore, the period of use was short, but it's missing a part. (See red circle in the photo) This is suitable as a replacement part, or for someone who already has the parts. Please note that it will be simply packaged. The legs may be disassembled for packaging. Included are one large wrench, two metal parts (probably for USA models), the box, and the instruction manual, both of which are labeled "M1" for some reason. (See photos) I used it on a Fender Japan Jazzmaster. The innovative Mastery Bridge, with its unique shape and saddle structure, improves string slippage issues common with Jazzmaster, Jaguar, and Mustang saddles. In addition to its functionality, it transmits string vibrations to the body without loss, resulting in a clearer and more powerful sound, achieving the best resonance and improving sound quality.